Mobile Phone and Location Update Method Thereof

1. A mobile phone comprising: a location update processing unit for generating a control signal when identifying that the mobile phone frequently performs location updates in a predetermined time; a location area judging unit for judging whether the mobile phone frequently moves back and forth near a boundary of an overlapping area of two adjacent cells of the boundary area of two adjacent location areas in response to the control signal; a scope acquiring unit for acquiring a predetermined scope when the mobile phone frequently moves back and forth near the boundary of the overlapping area, wherein the predetermined scope is a circle, the center of the circle is on the boundary of the overlapping area, and the radius of the circle is equal to one half of a distance between the center of one cell and the center of the other adjacent cell subtracted from the sum of the radius of the cell and the radius of the other cell; a scope judging unit for judging whether the mobile phone moves out the predetermined scope when the mobile phone frequently moves back and forth near the boundary of the overlapping area; and a selecting unit for controlling the mobile phone to perform a location update when the mobile phone moves out the predetermined scope; wherein when the mobile phone does not move out the predetermined scope, the mobile phone does not perform a location update.

2. The mobile phone as recited in claim 1 , wherein the scope judging unit is a motion sensor for periodically calculating a distance between the mobile phone and the center of the predetermined scope and judging whether the distance is greater than the radius of the predetermined scope.

3. The mobile phone as recited in claim 2 , wherein when the motion sensor calculates that the distance is greater than the radius of the predetermined scope, the mobile phone moves out the predetermined scope; and when the motion sensor calculates that the distance is equal to or less than the radius of the predetermined scope, the mobile phone moves within the predetermined scope.

4. The mobile phone as recited in claim 1 , wherein the selecting unit is further configured for comparing with signal intensities of the current cell of the mobile phone and the other adjacent cell to get a compared value and judging whether the compared value is greater than a predetermined value when the mobile phone moves out the predetermined scope, when the compared value is greater than the predetermined value, the selecting unit controls the mobile phone to perform a location update; and when the compared value is equal to or less than the predetermined value, the mobile phone does not perform a location update.

5. A location update method adapted for a mobile phone comprising: identifying that the mobile phone frequently performs location update a in a predetermined time; judging whether the mobile phone frequently moves back and forth near a boundary of an overlapping area of two adjacent cells of the boundary area of two adjacent location areas; if the mobile phone frequently moves back and forth near the boundary of the overlapping area, acquiring a predetermined scope, wherein the predetermined scope is a circle, the center of the circle is on the boundary of the overlapping area, and the radius of the circle is equal to one half of a distance between the center of one cell and the center of the other adjacent cell subtracted from the sum of the radius of the cell and the radius of the other cell; judging whether the mobile phone moves out the predetermined scope; if the mobile phone moves out the predetermined scope, performing a location update; and if the mobile phone moves within the predetermined scope, not performing a location update.

6. The location update method as recited in claim 5 , further comprising: if the mobile phone seldom moves back and forth near the boundary of the overlapping area, performing a location update.

7. The location update method as recited in claim 5 , the step of “judging whether the mobile phone moves out the predetermined scope” further comprising: periodically calculating a distance between the mobile phone and the center of the predetermined scope; judging whether the distance is greater than the radius of the predetermined scope; if the distance is greater than the radius of the predetermined scope, judging that the mobile phone moves out the predetermined scope; and if the distance is equal to or less than the radius of the predetermined scope, judging that the mobile phone moves within the predetermined scope.

8. The location update method as recited in claim 5 , the step of “if the mobile phone moves out the predetermined scope, performing location update” further comprising: comparing with signal intensities of the current cell of the mobile phone and the other adjacent cell to get a compared value; judging whether the compared value is greater than a predetermined value; if the compared value is greater than a predetermined value, performing a location update; and if the compared value is equal to or less than the predetermined value, not performing a location update.